1. Field of the Invention
The present invention relates to a semiconductor device and a method for forming the semiconductor device. More particularly, the present invention relates to a stacked memory and a method for forming the stacked memory.
2. Description of the Related Art
Memories are used in various products such as mobile products, computers, and portable products. A typical memory device includes memory cells arranged two-dimensionally on a substrate. Customers want high-capacity, high-performance, and inexpensive memory devices, but it may be difficult to satisfy such demands with memory devices that only have two-dimensionally arranged memory cells.
For this reason, highly integrated memories having a multi-level or three-dimensional memory cell array structures have been proposed. In a multi-level memory cell array structure, memory cell arrays are vertically stacked on a substrate. A NAND flash memory may include NAND strings in which memory cells are connected in series, which may allow integration at a higher level than other types of memories. For this reason, flash memories having a multi-level array structure (stacked memories) are being actively studied. However, the stacked memories should be further studied for high reliability.